0029384: Visualization, TKOpenGl - basic integration with OpenVR

0029384: Visualization, TKOpenGl - basic integration with OpenVR

V3d_View::AutoZFit() is now called only before redraw
within methods V3d_View::Redraw() and V3d_View::Update().

Graphic3d_CView now holds Aspect_ExtendedRealitySession object.
Aspect_OpenVRSession implements new interface via optional OpenVR library.
Graphic3d_CView::ProcessInput() - added new interface method
which should be called for processing positional input (head tracking).

Graphic3d_Camera now allows setting custom stereoscopic Projection matrices.

OpenGl_Context::Camera() - context now holds Camera object
in addition to active camera matrices.

genproj.tcl has been extended to handle optional CSF_OpenVR dependency.